Performance Regression Observed in DeleteRange and CompactRange Operations Post-Commit ca7367a

[Gallopm]

Expected Behavior:
The execution time of DeleteRange followed by CompactRange operations should remain consistent or improve across commits, maintaining optimal performance for key-range deletions and compactions.

Actual Behavior:
After commit ca7367a, a noticeable performance regression has been observed. The average execution time for the following sequence of operations increased ~2%:

1. Deleting a range of keys using DeleteRange.
2. Compacting a larger key range using CompactRange.

Steps to Reproduce the Behavior:

1. Fill 300000 key-value pairs into the Rocksdb database, while the key format is key$i, and value is a string of length from 10 to 99.
2. Check out the commit immediately prior to ca7367a and run the following test code:

   rocksdb::Slice start_key("key300"), end_key("key500");  
   db->DeleteRange(rocksdb::WriteOptions(), db->DefaultColumnFamily(), start_key, end_key);  
   rocksdb::Slice start_key1("key200"); 
   rocksdb::Slice end_key2("key700");  
   rocksdb::CompactRangeOptions comp_options;  
   db->CompactRange(comp_options, &start_key1, &end_key2);  
   

   Measure the average execution time.
3. Check out commit ca7367a or later and run the same test code, measuring the average execution time again.
4. Compare the results. The post-ca7367a execution time should show a consistent increase in latency.

[zaidoon1]

cc @jaykorean thoughts on this?

[jaykorean]

cc @cbi42